Method and apparatus for the production of sonic or ultrasonic waves on a surface



March 1970 H. SCHNEIDER ,503,8fi4

METHOD AND APPARATUS FOR THE PRODUCTION OF SONIC 0R ULTRASONIC WAVES ON A SURFACE Filed April 25, 1967 5, LASER BEAM I0 SENS/N6 DEV/CE United States Patent (i METHOD AND APPARATUS FOR THE PRODUC- TION OF SONIC R ULTRASONIC WAVES ON A SURFACE Hellnrut Schneider, Jacob-Steffan-Strasse l4, Mainz (Rhine), Germany Filed Apr. 25, 1967, Ser. No. 633,498 Int. Cl. 1308b 7/04; 1305b 17/04 U.S. Cl. 134-1 Claims ABSTRACT OF THE DISCLOSURE A method and device for producing energy on a surface together with a jet of water for example to clean the surface. there being provided a nozzle for generating a liquid jet and a device such as a laser generator for producing, a laser beam coaxially with the liquid jet, o that when the liquid jet and laser beam strike the surface to be cleaned, there is a combined action between the jet and the energy of the laser beam.

BRIEF SUMMARY THE INVENTION i the full development of their effect, be used in hot suds and/or be agitated vigorously. The same is true of solvents of all kinds, if they are not able to transform the impurities into a true solution. The auxiliary means necessary to produce these effects are voluminous and expensive and yet fulfill their prtrpose only partially. Moreover, where the use of thermal energy, mechanical energy, and/ or kinetic energy can be used only insufficiently or not at all. for example on relatively large objects, such as buildings, automobiles, ships, streets and the like, cleaning becomes very expensive, and sometimes even imprac- I ticablc. Also for objects which due to their size and complex form have inaccessible surfaces, effective cleaning aids were heretofore unusable, and a simple liquid jet was used. The liquid jet, which is of particular importance, offers in itself an abundance of advantages, which, however, are so weakened in their sum of disadvantages, not overcome until now, that only in the rarest cases could a really satisfactory end result be achieved with a liquid jet.

it is known, for example, that in the cleaning of vehicles. a liquid jet directed onto the dirty areas with great pressure removes the coarsest impurities lull is unable to take away the liner particles on the surface. Direct con- ;act and rubbing with a brush, sponge and the like is necessary to eliminate this residue of dirt. liven when adding surface-active substances, a lacquered surface cannot be cleaned with the liquid jet alone so that it appears visually more or less clean, because the remaining fine dirt particles produce a dull, cloudy appearance on the surface. The addition of thermal energy improves matters but is uncconomical. especially because much of the thermal energy applied is lost outside of the actual sphere of action.

An attempt has been made to add to the liquid jet other forms of energy, as for instance a pulsing, the frequency of which can be ultrasonic. The latter would be most Hce effective if a good deal of the applied energy were not lost outside of the actual sphere of action on the surface to be cleaned. Known for example are devices with which ultrasonic sound i generated inside a vessel containing a liquid, and also known 'are devices which impart pulscs to a liquid jet up to the ultrasonic frequency range. in the case of the liquid container it is possible to set the entire contents thereof in vibration. With a liquid jet,'=however, the ultrasonic vibration is produced in the liquid before it leaves the outlet, that is. not in the free jctitself. Although the pulses do propagate within the free jet, only a fraction of the original energy still exists, at the point of impingement of the jet on the surface to be cleaned.

ln controdistinction. an object of the inuution is" to provide a method and device by means of which energy pulses, in particular sonic or ultrasonic pulses, or heat,

can be produced within a free liquid jet as close as possible to the region of the desired zone of operation, that is, at the point of impingement on the surface tobe cleaned;

This objective is achieved with the method according to the invention in that in a free liquid jet directed onto a region of a surface at which energy pulses are to be produced, before or in the outlet of the apparatus producing the jet, a beam. substantially coaxial with the liquid jet, of parallel or convergingencrgy rays is focused onto said region. The rays are transformed into sonic; or ultrasonic waves or into heat near or at the point of'impingement of the liquid jet on the sr rrfacc.

When using parallel radiation (in thc rang".- bctuccn infrared and ultraviolet) the energy inherent in the radiation is liberated only at the point of impingement of the liquid jet on the surface to be cleaned, in the fcrnr of heat or ultrasonic waves. This presupposes that the liquid does not offer any appreciable resistance to the radiation energy at least in the region of-the jct length (cl-car liquidl. The radiation energy can be emitted intermittently, that is, in pulses, so that an additional desired pulsing effect is obtained at the point of impingement of the liquid jet. Likewise, radiation high in energy can= be concentrated by an optical system at any point of the free jet. so that intensified high energy is liberated thcrcat in the case of the impingement of the radiation. The radiation can impinge either on the surface to be cleaned itself, or on particles which=are added to the liquid, with the object of converting the radiation into heat or mechanical energy in the region of the focal point zone, of the energy radiatiomAlso optical systems may be used which produce several focal zones or focal points more or less'removed from each other within the free liquid'jet.

Laser radiation may be used in particularly advimtageous manner as energy rays. With a device for the production of laser rays, one can produce an almost absolutely parallel cncrgy radiation. in particular coherent li ht. without major energy losses occurring within the radiation producing device and on the path of the radiotio'n outside the producing device for inipingi-mcnt on surfaces. The radiation emitted by a laser dcvicc passes through transparent media practically without his the case of a straight transparent liquid jet. the radi propagating in it in the direction of its longitudinal axis is fully maintained up to the point of ir-npingemcnt of the liquid jet. it is even found that with a slight. curvature of the liquid jet. the energy radiation propagating rectilinearly is reflected at its outer faces and thus accompanies the liquid jet at least in part fully in its curvature. Due to its coherence, the laser radiation can be concentrated exactly at predetermined regions by corresponding optical systems. i

The energy inherent in the parallel rays of the laser beam is sullicient to produce ultrasonic waves in a liquid medium, with formation of the desired cavitation, where in quick succession small vacuum spaces or respectively vapor bubbles are fortued. If this occurs in the immediate vicinity of or in local coincidence with the dirt particles to be removed, these are detached from the surface and carried away in the liquid. The forces of adhesion which cause the finest dirt particles to adhere to a surface are sufficient to withstand the forces produced by a surfaceactive substance, so that the surface-active substance is unable to penetrate between the surface and the particle. This is not the case when waves of ultrasonic frequencies are added or used alone, whereby all particles are set in resonance and thus move in relation to the surface. Surface-active substances can then fully surround the particles. liven without the joint action of the surface-active substances, the particles are removed.

Hazards due to unintentional directing of the laser ray onto living organisms or overshooting are very largely avoided in that by reflection of. the radiation at the inner wall of the liquid jet due to so-called total reflection at some distance from the outlet opening of the water jet, and upon the division thereof, the laser radiation is transformed into diffiused light. An arrangement can easily be constructed where the laser radiation is developed only in the presence of the liquid jet.

The danger of damage to a surface due to direct impingement of a laser ray thereon is largely eliminated on the one hand, by the fact that the laser ray is unable to penetrate into the material, and on the other hand, by the ample cooling afforded by the presence of the liquid.

The method of the invention can serve also to impart ultrasonic energy to movable or other bodies to which ultrasonic energy cannot be ordinarily imparted or can be imparted only under unfavorable conditions. Thus a higher cutting speed or machining on lathes can be attained by ultrasonic sound, which may be produced with the device described directly at the cutting or machining region. The laser ray-conducting and ultrasonic producing liquid jct can be utilized in a great number of fields. as it can be used in convenient manner at any desired point and is readily movable.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION OI 'I'I-IE INVENTION Referring to the drawings there is sIIUWlI diagrammatically in FIG. I an arrangement wherein a nozzle 1 is fed with liquid from a pipe I to generate a liqrrid jet 2. The

riqnid jet is directed towards a surface 3 which may forexample be a surface which is to be cleaned.

A laser generator 4 is positioned adjacent the nozzle to generate a beam 5 of coherent light which is directed substantially coaxial with the liquid jet 2 and which contacts the surface 3 within the confines of the liquid jet 2. The liquid jet is formed of clear liquid so as not to constitutc any resistance to the radiation energy of the beam 5. The laser beam releases energy in the region of impingement with surface 3 in the form of ultrasonic waves. The combined effect of the ultra onic wa ,W'ncration and the liquid jet 2 on the surface 3 is LIIL'K. tr: tr is move all dirt particles froru the sur face 3 and thereby leave the same cleaned. It is also possible to utilize the beam 5 so that heat is generated in the region where the jet impinges on the surface 3 and the combined eflect of tue jet with the heat generation can also be employed to clean surface 3. Y

.-\n optical device 6 may be fitted on the laser gcnctafor 4 for the purpose of optically focusing the beam of rays 5 on the surface 3.

In the modified arrangement shown in-FIG. 2, an optical device 7 is fitted to the laser generator for the purpose of generating a plurality of individual spared beams 5a, 5/). i

The liquid jet 2 may be composed of ordinaryrwater or it may contain water with surface active agents which aid-in the removal of the dirt particles from th surface 3.

'The laser generator 4 develops hc'at during its operation and .for cooling purposes the pipe I may be formed with a coil C which surrounds the laser generator for cooling the same with water flowing therein.

In FIG. 4 there is shown a supply means 8 for the additionof particles to the liquid which is being fed to nozzle 1. The particles serve to transform the radiation energy from the beam 5, striking them into vibration energy thereby aiding in the removal of dirt particles from the surface 3. A valve 9 serves to control the quantity of particles introduced into the liquid fed to the nozzle, thereby controlling the magnitude of the vibration energy on the surface 3. Similarly, control of the frequency of the generation of pulses of the laser beam 5 serves to regulate the magnitude of the vibration energy at the surface 3.

In order to prevent the danager of damage to surface '3 due to direct impingement thereon of the laser beam 5 without the water jet, there is provided a device It) which is coupled to the laser generator 4 for controlling the operation thereof, in accordance with the flow of liquid from pipe P. In particular, the water sensing device 10 serves. to permit operation of the laser generator 4 only when liquid is present in the pipe I and is flowing from the nozzle 1 Although the invention has been described hercinabove in conjunction with several illustrated embodiments; it is apparent that numerous modifications and variations of these embodiments will bricorne evident to those skilled in the art without departing from the scope and s irit of the invention if defined by the attached t'lziittt;.

What is claimed is:

.l. Apparatus for generating energy at a surface comprising means for producing a liquid jct 'aud for direct ing said jet against a surface. means for ruojccting a beam of rays having radiation energy within the jet to- \vardssaid surface. the radiation energy of said I-t.ltll of rays being converted in the region where the lfqtli(l.j0l strikes the surface into sonic or ultrasonic Waves or heat, and an optical system disposed in the path of said bcani for focusing the beam within the liquid jet. l

2. Apparatus as claimed in claim 1, wherein said optical system includes means for producing a plurality of individual beams of high energy concentration.

3. Apparatus as claimed in claim 1 comprising means coupling the two first said means such that the means which projectsthe heam of rays is operative only when References Cited the liquid jet is produced. I v UNTED y 4. A method of generating energy at a surface, said a w q I H v method comprising directing a free liquid jet against a surface, and projecting. substantially coaxially within the 5 3,373,752 3/1) out: jet, a beam of laser rays having radiation energy which 4 1 is added to that of the liquid jet. said radiation energy MORRLS WOUX' Lxmmm being converted. in the region where the liquid jet strikes D. G. MILLMAN, Assistant Examiner the surface into sonic or ultrasonic waves or heat.

5. A method as claimed in claim 4 comprising opti- 10 U.S Cl. Cally focusing the beam of rays on the surface. 134 l98, 201; 239 4 m2; 

